Find the excess pressure:

Find the excess pressure:
(i) inside a liquid drop,
(ii) inside liquid bubble, .
(iii) inside a bubble in liquid

(i) Inside a liquid drop. Consider a liquid drop of radius R. The molecules lying on the surface of liquid drop, due to surface tension will experience resultant force acting inward to the surface.
Let S = Surface tension of liquid drop P = excess pressure inside the drop Due to excess of pressure, let there be increase in the radius of the drop by a small quantity in figure

Then work done by the excess pressure. W = Force x Displacement